1. Field of Invention
The present invention relates generally to the field of communication protocols. More specifically, the present invention is related to transferring a frame relay protocol over an Internet protocol.
2. Discussion of Prior Art
One of the most popular packet-switching protocols for connecting devices on a Wide Area Network (WAN) is the Frame Relay. Frame Relay networks in the U.S. typically support data transfer rates at T-1 (1.544 Mbps) and T-3 (45 Mbps) speeds. In fact, you can think of Frame Relay as a way of utilizing existing T-1 and T-3 lines owned by a service provider. Most telephone companies now provide Frame Relay service for customers who want connections at 56 Kbps to T-1 speeds. (In Europe, Frame Relay speeds vary from 64 Kbps to 2 Mbps.)
Frame Relay, a popular Legacy protocol, is capable of supporting large bit rates and, in the U.S. is quite popular because it is relatively inexpensive. Unlike older protocols, i.e. before the 1990""s, the Frame Relay minimizes error correction, editing and retransmission features, sparse data management operations (e.g. traffic acknowledgment), etc. Because todays"" communication systems are built using high quality communication networks (low bite error ratesxe2x80x94BERs) which often perform much of the overhead associated with completion of transmissions, the need for extensive embedded features no longer exists. The Frame Relay, absent one or more layers, enables a faster less cluttered transmission protocol.
The present communications revolution has been focused on the Internet and World Wide Web (WWW) with emphasis on the Internet protocol (IP). Frame relay uses variable length protocol data units (PDUs). However, Frame Relay does not work well with variable delay units as typically found in Internet carried digital voice and video. The prior art has failed to teach a viable solution to handling Frame Relay (FR) over Internet Protocol (IP).
Each of the below described references teach methods of interworking functioning (IWF) for differing protocols across various communication standards. However, none of the references provide or suggest the present invention method of Frame Relay over IP.
The patent to Essigmann (U.S. Pat. No. 5,850,391), assigned to Telefonaktiebolaget L M Ericsson, provides for a Shared Interworking Function Within a Mobile Telecommunications Network. Essigmann discloses a method and apparatus for communicating interworking function (IWF) control data between a mobile switching center (MSC) and a telecommunication node as illustrated in FIG. 5 (U.S. Pat. No. 5,850,391). The serving MSC encapsulates the identified IWF control data into an optional parameter within an integrated service digital network user part (ISUP) signal. The MSC then transmits the ISUP signal encapsulating the IWF control data towards the telecommunications node.
The patent to St-Pierre et al. (U.S. Pat. No. 5,901,352) provides for a System for Controlling Multiple Networks and Associated Services. This reference describes a system for enabling network convergence and interworking between multiple communication networks. FIG. 1 (U.S. Pat. No. 5,901,352) illustrates telecommunication network (10) with mobile switching center (30) that includes interworking function (IWF) for providing communication over different protocols.
The patent to Bhalla et al. (U.S. Pat. No. 5,949,773), assigned to Motorola, Inc., provides for a Method for Transferring a Data Signal in a Wireless Communications System. Disclosed is a system for transferring a data signal in a communication system. Source selection distribution unit (SDU) (248) in FIG. 3 (U.S. Pat. No. 5,949,773) converts incoming data signal (107) to frame relay switched virtual circuit (FR SVC) protocol suitable for conversion by source interworking function (IWF) (214), thus eliminating the need for protocol conversion by source SDU (170).
The non-patent literature entitled, xe2x80x9cTrends for 1999: Interworking Between Frame Relay and IP networksxe2x80x9d, Network World Fusion, Jan. 1, 1999 (www.nwfusion.com) provides a brief look at IP traffic bound for a destination on a Frame Relay network which gets concentrated to one or more sites. At these sites, routers (or a routing function) also know the IP addresses at the ends of the frame relay PVC""s.
The patent to Pepe et al. (U.S. Pat. No. 5,742,668), assigned to Bell Communications Research, Inc. provides for a personal internetwork over wireless or wire-line communication mediums.
Whatever the precise merits, features and advantages of the above cited references, none of them achieve or fulfills the purposes of the present invention. These and other objects are achieved by the detailed description that follows.
A system and method of implementing interworking function (IWF) between frame relay and IP protocols and networks. The interworking function provides mapping and encapsulation functions necessary to ensure that service (protocols) provided to networks is kept unchanged. The present invention provides a Frame Relay service specific convergence sublayer (FR-SSCS) necessary to translate between the Q.922 and UDP/IP sublayer.